Electric furnace



Nov. 11 1924.

C. MiLLER ELECTRIC FURNACE Filed Nov 5, 1922 Patented Nova ll, 192% 1* w, chin one .LHLLZEE, F BRIDGEPOBT; CONNECTICUT, ASSIGNOR TO MANNING, MAX- PATENT OFFICE.

HELL 5;: 1983/3, INC., 0 NW YKIBK, N. Y., A COR'E'QRATION OF NEW JERSEY.

ELECTRIC FURNACE.

Application filed Kovemiaer 3, 1822. Serial No. 598,!69.

To all whom it may co-ncam:

Y Be it known that I, Gi-IARLESMILXZER, citizen of the United Stetes, resi ing at Bridgeport, in the county of Fcii'ield and State of Qonnecticut, have invented certain new and useful Improvements in Electiic Furnaces, of which the following is a full,

, clear, and exact description, such aswill en- ,cxpeiienced in. the connnei'c al able OllfilSSkli'lHl in the art to which it uppei'tains to make and use the same.

This invention relates to furnaces and.

more particularly to iinpi'ovements in electric furnaces intended for operation at high temperatures. J

in instances of his type diliiculty has been use of such furnaces by reason of the fact that. stthe high temperatures employed, suchloifexample, as in the melting of refractory metals like Monel metal, 'a great wastage oi the wells of the furnace takes place whereby the cost and trouble of maintaining the in noce and of conducting separations therein is great.

An object of this invention is to produce a furnace in which such high temperatures can be quickly and economically attained without serious wastage cl"'tlie iui'nece' lining,

A further object ofthis im 'ention is to provide a process by which substances, pun ticulaily refractory i'netals, mew be melted economically and effectively ru -id wi hout undue "admixture of imputities.

Other advantages will be in part obvious and in part pointed out hereinafter. -i

The invention accordingly consists in the several steps and the relation and state of one or more of such steps with i'elation to each of the others thereof and in the features of construction, combinations of elements and arrangemeutsbf parts, both of which will be exemplified in the process and construction hereinafter set forth, the mope and -,appliont1on of which will be indicated in the following claims.

[In the accompanying drawing WliBPEHI there is shown one of the la-3710115 possible embodiments of the invention the figure rep-resents avertlca-l section through. the

centei' I a furnace.

As '11 ustrcted, the furnace comprises a receptacle 1, and en internal sout'cc 03': heat 2, which s'o-urce in order to produce high tempeiatures, preferably employs an electric arc. i i

In older that this source'of heat may be concentrated as much as possible upon the nmt'erlal to be heated, it is placed in the interior of thecrucible and in such aposit-ion as to directits efiect downwardly upon the material to be heated.

' The interior of the crucible is preferably of an ovoid form, whereby the walls are positioned along substantially isothermal lines, when the receptacle contains its charge. Such formfmoreover, impartegreat strength to'the' receptacle while exposing a minimum surface to the action of the heated gases.-

In order, however, to permit and facilitcte the vinsertion of the heating element along the axis of the crucible, it is desirable that the crucible be truncated whereby an opening is formed at the top, as at 3, which may conveniently be closed by the heating element. x y This arrangement shown is provided with electrodes 4 and 5 carried-by a; suitable support 6 adapted to form n cover for the cmcible' It will be understood that the electrodes may be supplied with electric current from any suitable source; if a three-phasesource of current is employed it -may be convenient to provide three or four electrodes.

, Suitablemeans will be pro 'lided for controlling the electric arc. For example, they may be ivoted about the upper ends as at 7, where y they are caused to swing apart by the magnetic field generated aroundthe electrodes by the current flowing there? through, but it will be understood that any othelr suitable means of control may be ut1-. use

The receptacle is preferably formed from an interior crucible 8, contained within an outer vesseli), and the space between is filled with. a, suitable refractory material 10 befor example magnesia, or-

The walls of this spout, however, should be attached to the crucible as smoothly as possible, as for example, in the illustration the bottom Wall of the spout is made tangential to the interior wall of the crucible as at 14. By this construction there is little or no tendency for the crucible to crack at the juncture of the spout with the body even under the high temperatures to which it subjected.

It has been found furthermore that the life of the crucible may be materially lengthened and hence the expense of heating the material may be reduced by increasing the thickness of the Walls of the upper portions of the receptacle, particularly at or near the opening in the top as at 15. This may be due to the fact that it is in this portion of the furnace that the heated gases from the are rise and hence it is this portion of the walls which is subjected to the highest ternperatures. Furthermore, it has been found that the life of the crucible may be materially lengthened by increasing the thickness of the walls at the juncture of the spout with the body, as shown at 16.

While in j general the wastage of the crucible may occur by contact of the hot gases with the interior Walls, yet it will also be evident that the crucible itself will attain a high temperature and if its. exterior Walls were exposed to the air great loss of heat and-wastage of the crucible would occur from the exterior of the walls. For these reasons, the form of receptacle with its in terior crucible, exterior container, and intermediate insulator, is particularly advan 'tageous.

For different purposes dili'erent material may be employed from which to construct the crucible, but it has been found that where high heats are desired as in the melting of Moncl metal excellent results may be obtained from the use of a crucible made oi graphite.

As many changes could be made in the above construction and many apparently widelydii'i crent embodiments of this invention could be made Without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not. in a limiting sense.

t is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention, which, as matter of language, might be to fall therebetween.

Having described my invention, what I claim as new and desire to secure bylietters Patent, is:

'1. In a device of the character described, in combination, a crucible of graphite having an opening in the top thereof, the walls of said crucible being thickened near the top, a cover for said crucible adapted to fit said opening, and a pair of electrodes for an electric are suspended thereiroin.-

2. In device of the character described, in combination, a crucible of graphite having an opening in the top thereof-and a dis charge spout in the side thereof above the level of the bottom, the Walls of said crucible being thickened at the juncture of the spout with the body.

3. In a device of the character described, in combination, acrucible of graphite having an opening in the top thereof and a discharge spout in the side thereoi above the level of the bottom, the walls of said crucible being thickened'at the juncture of .the spout with the body and adjacent the top of the body.

4. In a device of the character described, in combination, a crucible of graphite having an opening in the top thereof and a discharge spout in the side thereol above the level oi the bottom, the walls of said crucible being thickened at the juncture of the spout, and adjacent the top thereof, a cover adapted to fit said opening, anda pair of electrodes for an electric arc suspended therefrom.

5. In a device of the character described, in combination, a crucible comprising a body of truncated ovoid form, having a spout upon the side thereof, the lower inner surface of said spout being substantially tangent to and extending upwardly from the lower inner surface of the body, the walls of said crucible being thickened above the level of the bottom of the discharge orifice of said spout.

6. In a device of the character described, in combination. a crucible of graphite comprising a body of truncated ovoid form,

having a spout upon the side thereof, the lower inner surface of said spout being substantially tangent to and extending upward ly from the lower inner surface of the body, the walls of said crucible being thickened above the level of the bottom of the discharge orifice of said spout.

in testimony whereof I aiiix m signature, in tin presence of two witnesses.

YHARLES lillLLElt. Witnesses CHAS. W. Pour, Gruo. i Koran. 

